This is a fun pattern to work - you cast on all the stitches needed for the bottom, and decrease every other row to the top. It can be made in two flat pieces (so there are arm seams) with either a fringed bottom or a ruffled edge. It can also be done on a circular needle.

I like the seamlessness of the one done in the round, BUT I found dealing with the center stripe very frustrating, because when every row is going the same direction, the contrasting thread for the center stripe is always on the opposite side of the stripe from where you need it, so it’s hard to get a nice, snug transition to the other color as you can with the back-and-forth flat-worked method. But it can be done, so the choice is yours. I only included circular needle instructions for the fringed version - to do the ruffled edge you would have to cast on anywhere from 606 to 722 stitches which would make me crazy!

I have also published a pattern for a matching poncho for an 18” doll (available in my store as “Fun Poncho for 18” Dolls”). Look for it if your girl would like one for her doll!